Lying down after the arm and hand numbness may be physiological factors, cervical spondylosis, diabetes, cerebrovascular lesions and other factors. 1. Physiological factors: after lying down in an incorrect posture, the arm is subjected to persistent compression, so that the blood circulation of the upper limbs is not good, there will be physiological arm and hand numbness, should improve the sleeping posture, and reasonable activities, can improve on their own, do not need special treatment. 2. Cervical spondylosis: may be related to long hours of work, chronic neck strain and other factors, lying down to sleep with a pillow too high, may lead to cervical spondylosis aggravation, the nerve innervating the upper limbs caused by compression, will cause arm and hand numbness. 3. Diabetes: diabetes for a long time, may lead to peripheral neuropathy, in the sleep may appear arm and hand numbness symptoms, may also be accompanied by drinking, eating, urinating and other symptoms. 4. Cerebrovascular lesions: lying down after the arm and hand numbness, and accompanied by numbness of the lower limbs, as well as headache, dizziness, nausea and vomiting and other symptoms, encounter vigilant cerebrovascular lesions, such as cerebral infarction or cerebral hemorrhage. Lying down after the arm and hand numbness, excluding physiological factors, but also accompanied by other clinical symptoms, it is recommended that timely medical examination and treatment.